Abstract: The polyacrylonitrile/polyvinylidene fluoride (PAN/PVDF) nanocomposite fiber membranes were prepared by the coaxial electrospinning technology using PVDF as the core layer and PAN as the skin layer. Structure optimization of PAN/PVDF nanocomposite fiber membrane was carried out by adding three different nanoparticles of nano-silica powder, fumed silica and silica sol to the PAN/PVDF nanocomposite fiber membrane and changing the extrusion speed of the skin-core layer solution. Meanwhile, its pore structure parameters, surface morphology, hydrophilicity and mechanical properties were studied by BET, SEM, water contact angle, fiber strength meter and so on. The results show that the conductivity of the solution after adding silica sol to the solution reaches 32.90 μL/cm, the PAN/PVDF nanocomposite fiber membrane has the best mechanical properties, and the longitudinal breaking strength reaches 13.02 MPa. The quality factor of mask cloth containing silica sol reaches 0.0236, which is much larger than the quality factor of pure polypropylene (PP) non-woven, which is 0.0127, and the filterability is significantly increased.